The present invention relates to recording apparatus wherein graph sheets are used as a recording medium to record information, the sheets being moved at a certain rate in accordance with the passage of time. At least one recording instrument, such as a wire pen, is arranged to move in a plane parallel to that of the sheets which rest on the support. The recording apparatus also includes a lid which can be pivoted between closed and open positions to allow the sheets to be removed and replaced, and an arrangement which allows the recording instrument to be moved into and out of contact with the sheets as the lid is swung.
In recording apparatus of the above type, which is not generally designed as a tachograph wherein a recording instrument is arranged in one portion and a recording medium in another portion of two rotatably connected parts (a lid and a housing), a problem arises in regard to removing or replacing the recording medium (e.g., graph sheets) without contacting the recording instrument. In cases where graph sheets are automatically evaluated, it is essential that inadvertent contact between the sheets and the recording instrument be avoided since markings or scratches by the instrument will give rise to errors in evaluation. On the other hand, damage of the recording instrument, especially to pen points, must be avoided since such points often include fine wire recording electrodes or jewels which are relatively brittle and subject to fracture.
It is known to provide one or more recording instruments with elastic parts to separate the instruments from the recording medium when the lid of recording apparatus is opened. It is also known to elastically mount the recording instruments themselves, or their supports, so that the instruments are automatically lifted from the recording medium when the lid is opened. In order to protect the recording points of the instruments, suitable shielding parts have been provided which present only a slotted opening through which the recording medium is introduced. When opening the lid of this apparatus, the recording instruments are tilted within the shields so that their recording points become inaccessible. When circular graph sheets are used as the recording medium, on which sheets recordings are made over most all of their entire radial extent, the shields and the centering and driving mechanism for the sheets are situated relatively close to one another. Accordingly, introducing the sheets beneath the shields is a rather complicated process. Improved handling in these cases is made possible by allowing the recording instruments to remain only partly covered.
In recording apparatus of the type wherein recording instruments are arranged between a recording medium and a swinging lid, and the instruments are relatively easily accessible, it is necessary to arrange the bearings and the guide mechanism for the recording instruments, and particularly their adjustment mechanisms, so that they cannot be tampered with in order to reduce the danger of unauthorized manipulation.
The known recording apparatus has not proven to be fully satisfactory, especially in those cases where the recording medium is to serve as an important document. For example, a high degree of security is required when the apparatus is used as a tachograph, where it is essential that the recordings must not be falsified. However, when the lids of the known apparatus are opened, the recording instruments can be moved manually, either directly or by way of operating parts connected to the lid, onto the recording medium. Then, by moving the recording medium in its normal driven direction, recordings can be simulated.
An object of the present invention is to overcome the above disadvantages of the known recording apparatus so that the recording instruments cannot be brought to their normal recording positions when the lid of the apparatus is opened, and to provide secure recording apparatus which can be produced and operated at minimum cost.
In accordance with the present invention, a recording apparatus comprises a planar support for supporting a recording medium. At least one recording instrument is arranged to be movable relative to the support to provide a recording on the medium when the instrument is moved into contact with the medium, and the medium is driven at a given rate. A lid for covering the recording medium is arranged for pivotal movement about a hinge axis, between open and closed positions relative to the support, to move the recording instrument into contact with the recording medium when the lid is in the closed position, and to lift the instrument out of contact from the medium when the lid is in the open position. A movable guide part contacts the recording instrument to lift it out of contact from the recording medium when the lid is moved to the open position. A drive arrangement between the lid and the guide part lifts the guide part as the lid is pivoted toward the open position, so that the recording instrument is held at a position out of contact with the recording position.
In a preferred embodiment, the lid has a projecting hinge part through which the hinge axis extends. This hinge part has a cam surface on its periphery which surface extends arcuately about the hinge axis and rotates about the hinge axis when the lid is opened and closed. The drive arrangement which includes the hinge part, also includes an elongated lever which is pivotally supported between its ends. The guide part contacts one arm of the lever, and one end of an elongated rod contacts the other arm of the lever. A roller is arranged between the other end of the rod and the cam surface on the hinge part.
Preferably, the recording apparatus also includes a pivotally movable shield for protectively covering the recording instrument, the shield being operatively associated with the lever. One or more connecting members may then be arranged between the shield and the recording instrument to move the instrument out of contact with the recording medium when the shield is raised above the instrument by the lever.
Aside from fulfilling the objects of the invention, the present recording apparatus offers security against unauthorized manipulation of the recording instrument. The elements of the drive arrangement between the lid and the recording instrument are of simple form and easily engage one another during operation. Operating safety is thereby improved while manufacturing and installation costs are reduced, since wide tolerances can be allowed. When a shield in the form of a hood is used for the recording instrument, it is desirable that the shield be made in such a manner that it be raised above the recording medium together with the recording instrument. Also, the shield itself may serve as a driving element for the recording instrument which can be lifted by a rigid member connected between the shield and the instrument.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention .